Waiting call indicating device for semiautomatic telephone systems



Filed Feb. 15, 1,946 3 Sheets-Sheet 1 1949 E. A ERICSSON ET AL 2,491,171

WAITING CALL INDICATING DEVICE FO SEMIAUTOMATIC TELEPHONE SYSTEMS M v KSNR F A v KGVI U5 Fig.

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Dec. 13, 1949 E. A. ERICSSON ET AL 2,491,171

WAITING CALL INDICATING DEVICE FOR SEMIAUTOMATIC TELEPHONE SYSTEMS Filed Feb. 15, 1946 5 Sheets-Sheet 2 REG RRJ

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WAITING CALL INDICATING DEVICE FOR SEMIAUTOMATIC TELEPHONE SYSTEMS Filed Feb. 15, 1946 3 Sheets-Sheet 5 GR! 6R2 V v Fig. 5

Lima/81017025 EH/ZWZ'DZLCG-SOZI/ C ra/o0 6.263 as Patented Dec. 13, 1949 UNITED STATES PATENT OFFICE 2;491,1*1i wsrrmc ett lii carmcp'avmg 130 sEMIAoToMATIo TELErHoNE SYSTEMS Erie Ar /id Enessen and Anton Christian seetbaeus, Stockholm; Sweden; assi imys to Tele-' foriaktiebolag'et L M Ericsson,

Stockholm;

Sweden; a company of Sweden An iieatimtetmar 13, 19146,, QS'erfiai No. 647,2.t In Sweden March 15, 1945 4Claims. (Cl. JUN-27) It often happens in telephone networks, that calls to certain subscribers lines nlust be arranged in a queue. Special manual operating boards are arranged Within local networks, to which the subscribers may apply when there arise difficulties to get through to a certain subscribers number. On larger trunk exchanges there is an operating board for waiting calls; which takes care of all the trunk calls to sub scribers lines on which there is a queue. In such cases, calls to lines connected for waiting calls must be indicated in a special way,, in order to avoid repeated resultless calls. It is known how to arrange that for trunk calls by means of a signal from the operating board for Waiting calls to the line selector in the connection, over which the operating board for waiting calls is connected to the subscribers line in question, said signal then producing such a change in the circuits over the helping wires of the subscribers line, that calls to the subscribers line are met by a special tone, indicating that the line is connected for waiting calls. This however requires devices both expensive and complicated.

The present invention intends to produce a simple and good solution of the above mentioned problem and achieves it, the calls being connect ed by means of registers, which are set accord"- ing to the number of the subscriber's lines and are connectable, one at a time, to a control device common to all the registers, the connecting links pertaining to a manual operating board moreover being arranged for the connection of calls in a queue to subscribers lines, said connecting links being provided with indicating devices which, in relation with the connection of a communication from the operating board for waiting calls, are set in accordance with the nur'riber of the called subscribers line and are connected with said control device by means of circuits, over which it is controlled if the setting of a register, which is connected to the control device by a subscribers establishing a cominunica tion, corresponds with the setting of one of said indicating devices, in which case the control device emits a signal to said register, either a special queue-indicating tone being sent to the caller, or the caller automatically being connected to the operating board for waiting calls.

The invention will be more closely described with reference to the accompanying drawings Figs. 1-3, which show an embodiment of the same for automatic trunk traffic. It is obvious; that the invention may as well be applied to au- 2 tomatic local tra'fiic or to half automatic trunk bra 11 10;

Fig; 1 shows the traific paths within a trunk exchange I, which cooperates with a local ex change L-. Trunk calls are dispatched over connecting links ISNR, which are connected to a register REG over a finder RS. After the regis ter having been set, the trunk call is connected over the group-selector IGVI to the group-selector GV2 of the local exchange and thereafter further to the called subscriber. If a queue has had to be arranged for the trunk calls to a sub scribers line, a communication is set up from a; trunk operating board for waiting calls KB over a connecting link KSNR connected to the board and a group-selector KGVI to said subscribers line in the local exchange.- A register REG thus takes partin the switching operation in a known way. At the same time as the register REG is set according to the subscribers number, for instance by means of impulse trains, an indicating device M'pertaining to the connecting link KSNR is also set in accordance with the subscribers number. v, 7 7

There is acontrol device K common to all the registers REG and the indicating devices M, to which control device the registers REG can con nect. themselves one at a time, the indicating devices M, on the other hand, being connected to the control device over special indicating wires as soon as they have been set. V K

It may be arranged either so, that the registers REG, foreach communication they establish, connect themselves to the control device K and examine iithe ealledsubscriber is connected to the operating board for waiting calls KB, or so, that the line-selector of the local exchange can emit a signal to the register REG on the called line being busy, the register then connecting itself to the control device K and examining if the called subscriber is connected to the operat ing board for waiting calls;

If the register receives a signal from the control device K showing that the called subscriber is connected to the operating board for waiting calls, the circuits of the register are switched either so that the caller receives a special tel-1e; or so that the caller is automatically connected to the operating board for waiting calls over the selectors IGVI and TLV, a lamp then glowing at the connecting link KSNR iii the operatin board for waiting cans, theindicating device of which is set on the telephone number of the called subscriber; The operator in the operating board for waiting calls is thus iniormed of the called 3 subscribers number already before answering the call.

Fig. 2 and Fig. 3 show the circuits important for the invention in a 4-figures system arranged. according to the principles mentioned in Fig. 1.

In each register REG there are four registering selectors Rel-Re4, each of which has an extra contact row, which is drawn in Fig. 2. There are likewise, in each of the indicating devices M, four registering selectors Rel lRel l, one for each figure of the 4-figures subscribers numbers. There are 10 wires t1t1o, one for each position corresponding to a figure in a registering selector ReIRe4 or Rel lRel4, said wires being common to all the registers REG and the indicating devices M. Said wires are multiplicated to all the registers and indicating devices. On a communication having been set up over a connecting link KSNR in the operating board for waiting calls, relay RM'l attracts for the corresponding indicating device M, contacts I! l-l 12 then being closed.

The common control device K is shown in Fig. 3 and contains a rotary selector V with three contact rows A-C and a stepping magnet VM. A relay chain may naturally replace said selector. The selector V is in position 1, when the control device is at rest, contact I then being broken and contact 2 closed.

When the switching operation in a register REG points out, that it has to control if the called subscriber is or is not connected to the operating board for waiting calls, a contact set G in Fig. 2 is actuated. The positive pole of the exchange battery is indicated by in the following, and its negative pole by negative. On the drawings, the symbols and are being used. The following circuit is completed: contact set G, winding on relay RRI, discharge lamp GL. contact 2 l, wire e, contact strip B position 1 (Fig. 3), winding on relay GRl, contact 2l3, resistance r, to V, which is the negative pole on a battery with a tension high enough to allow the discharge lamp GL to glow. The positive pole of said battery is connected to If the control device K is free, the discharge lamp KL glows, the voltage drop over resistance r then preventing other discharge lamps GL in other registers from glowing. If several registers attend to the control device K, only the discharge lamp, which has the lowest striking voltage, glows.

Relay RRl attracts its armature. Contacts l|--l'| are closed. Contact l5 short-circuits discharge lamp GL. Contacts lll4 close the circuit from the selectors Rel-Re l over wires a, b, c, d to the position in the control device K. Relay GRI attracts its armature. Contacts 2! l 2l6 are actuated. Stepping magnet VM receives current over contacts 2| 6 and 2 and selfbreaking contact 3 for VM. Selector V moves to position 2. Contacts l--2 are actuated. The following circuit is completed, if the first figure of the called subscribers number is registered on the selectors Rell in one of the indicating devices M of the operating board for waiting calls: contact strip A position 2, winding on relay one, wire kl, con tact I12, winding on relay RMl, selector Rel I, one of wires t1t1n, selector Rel, contact ll, wire a, contact strip B position 2 to negative. Relays RMI and GR4 attract their armatures. Contacts Ill-l l2 and 4'.43 are actuated. Relays RMI and GR4 are self held over contacts H2 and ll, resp., wire m and contact 2l5. Selector V continues to position 3.

If the first figure in the called subscribersnumher is not registered on selector Rel l in one of the Y negative.

indicating devices of the operating board for waiting calls, relay GRA does not attract its armature. On selector V reaching position 3, the following circuit is completed: contact strip C position 3, contact 42, wire f, contact l6, winding on relay RR2 to negative. Relay RR2 attracts its armature and is self held over contact 22 and contact set G, and breaks the current for relays RRI and GRI, which release their armatures. The register REG is thus freed from the control device K. It has thus been indicated in the register, that the called subscriber is not connected to the operating board for waiting calls. The control device K returns to position 1. If the selector V had been replaced by a relay chain, the replacement of the control device would have been efiected immdiately, which is important by large exchanges, especially when there is no busy signal from the line selector of the local exchange to the register REG and all the connections must apply to the control device.

In the following it is supposed, that relay (3R4 and relay RMl attract their armatures at least in one of the indicating devices M. On selector V reaching position 3, a new circuit is completed: contact strip A position 3, winding on relay GR5, wire k2, winding on relay RM2, contact lll, selector Rel 2, one of wires tr-tm, selector Re2, contact 12, wire I), contact strip B position 3, to negative. Relay RM2 can now attract its armature among the indicating devices, in which relay RMl has attracted its armature, if the setting of Rel2 corresponds to the setting of Re2. Relay GR5 then also actuates. Contacts I2l-l22 and til-52 are also actuated.

When selector V reaches the positions 4 and 5, what has been described above with regard to relays RMl and RM2. together with GR4 and GR5 is now repeated for relays RM3 and RM4 together with relay GRS. No relay corresponding to GRfl-GRB in the control device is needed for the control circuit over position 5. If all the relays RMl-RM4 attract their armatures in one of the indicating devices, that means, that said indicating device is set on the same subscriber's number as the register REG connected to the control device. On relay RMll attracting its armature contacts l4ll42 are closed. The following circuit is completed: contact l4l, winding on relay RM5, contact I62, wire h, winding on relay GR3, to negative. Relays RM4 and GR3 attract their armatures. Contacts 15!, 23l and 232 are actuated.

On selector V reaching the position 6, relay GR2 attracts its armature due to the following circuit: contact 2M, winding on relay GR2, contact strip B position 6, to negative. Contacts 22 |222 are actuated. The selector V hereby remains in position 6.

If the setting of selectors Re4 and Rel 4 had not been the same, relays RM4, RM5 and GR3 would have attracted their arm'atures and the following circuit completed: contacts 232 and 22l, wire f, contact l6, winding on relay RR2, to Relay RR2 would then, as described above, have released the register REG and freed the control device, in which, after relays GRl and GR2 having released their armatures, selector V continues to position 1.

It had been supposed, that relay GR3 had attracted its armature and contacts 23l232 been actuated. The following circuit is completed: contact 23L wire g, contact ll, winding on relay RRS to negative. Relay RR3 attracts its armature and is self held over contact 3i and contact set G. At the same time, relay RR3 actuates a number of contacts, which are not shown in the figure and which efiect such a switching of the circuits of register REG, that the communication which is being connected over a group-selector IGVI in Fig. 1 and a line selector TLV is connected to the operating board for waiting calls. Among the lines existing between the selectors TLV and the operating board for waiting calls, one only is pointed out, viz, the one which is indicated by contact ['51 in Fig. 2. Selector TLV tests the winding on relay RM5, which attracts its armature and is self-held over contact ltl. Contacts ISL-I66 are actuated. The lamp KL glows. The communication with the operator of the operating board for waiting calls is obtained over contacts M5 and W6. The circuits for relays RM'i, RM@ and GR3 are broken and said relays release their armatures. Contact 232 is closed and relay BB2 in the register REG attracts its armature. Contact 2| breaks the circuit for relays RRI and GRI, after which the register REG and the control device K are freed. Relays RM|RM4 in the indicating device M release their armatures, but the selectors Rel l-Rel remain in their respective position.

The contact rows Eek-Red in the register REG may at the same time suit other purposes, such as indicating the setting of a register on a lampfield common to all the registers and connected to the wires t1-tm one figure at a time being indicated by means of special circuits. Such lampfields exist in the control desks in large automatic telephone exchanges.

We claim:

1. In an automatic telephone system arranged to permit queueing of calls to certain lines, a plurality of subscribers lines, a plurality of registers each capable of being set to register the designation of a called subscribers line, selectors for connecting an idle one of said registers to a calling subscribers line upon initiation of a call thereover to conduct impulses corresponding to the designation of a called subscribers line to said idle register to set the same, an operator's board, 4

links connected to said board and to said selectors to extend certain subscribers lines to said board, an indicating device for each link and capable of being set to register the designation of said certain called subscribers line, a control device common to all of said lines, said registers and said links, means for connecting said registers one at a time with said control device, indicating conductors common to all of said registers and said links, means in said control device connected to said indicating conductors for comparing the registration set in a register with the registrations set in said indicating devices, means under the control of the last-named means for emitting a signal to said register in response to correspondence of said registrations, and means in said register responsive to said signal for afiord- .ing an indication to the calling subscriber.

2. The invention of claim 1, in which the means in said register responsive to said signal is arranged to disconnect the control device therefrom, and concurrently to connect a tone source to the calling subscriber's line.

3. The invention of claim 1, in which the means in said register responsive to said signal is arranged to disconnect the control device therefrom and concurrently to extend the calling subscribers line to said operators board.

4. The invention of claim 1, in which the means in said register responsive to said signal is arranged to extend the calling subscribers line to that indicating device set to correspond to the registration in said register, and concurrently to disconnect said control device therefrom.

ERIC ARVIED ERICSSON. ANTON CHRISTIAN JACOBAEUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,249,486 Molnar July 15, 1941 2,291,497 Newstedt July 28, 1942 2,352,107 Kessler June 20, 1944 

